Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N52/00—Hall-effect devices
  • H10N52/101—Semiconductor Hall-effect devices
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R33/00—Arrangements or instruments for measuring magnetic variables
  • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
  • G01R33/06—Measuring direction or magnitude of magnetic fields or magnetic flux using galvano-magnetic devices
  • G01R33/07—Hall effect devices
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R33/00—Arrangements or instruments for measuring magnetic variables
  • G01R33/0052—Manufacturing aspects; Manufacturing of single devices, i.e. of semiconductor magnetic sensor chips
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L23/00—Details of semiconductor or other solid state devices
  • H01L23/48—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor
  • H01L23/481—Internal lead connections, e.g. via connections, feedthrough structures
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10B—ELECTRONIC MEMORY DEVICES
  • H10B61/00—Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N50/00—Galvanomagnetic devices
  • H10N50/80—Constructional details
  • H10N50/85—Magnetic active materials
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N52/00—Hall-effect devices
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N52/00—Hall-effect devices
  • H10N52/01—Manufacture or treatment
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N52/00—Hall-effect devices
  • H10N52/80—Constructional details
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N52/00—Hall-effect devices
  • H10N52/80—Constructional details
  • H10N52/85—Magnetic active materials
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10N59/00—Integrated devices, or assemblies of multiple devices, comprising at least one galvanomagnetic or Hall-effect element covered by groups H10N50/00 - H10N52/00
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
  • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
  • H01L2224/42—Wire connectors; Manufacturing methods related thereto
  • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
  • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
  • H01L2224/4805—Shape
  • H01L2224/4809—Loop shape
  • H01L2224/48091—Arched
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
  • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
  • H01L2224/42—Wire connectors; Manufacturing methods related thereto
  • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
  • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
  • H01L2224/481—Disposition
  • H01L2224/48151—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
  • H01L2224/48221—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
  • H01L2224/48245—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic
  • H01L2224/4826—Connecting between the body and an opposite side of the item with respect to the body

Definitions

• Hall Effect magnetic field sensing elements are known.
• a Hall Effect element includes a so-called “Hall plate,” which is most often an epitaxial region (i.e., a layer) upon a substrate.
• the epitaxial region is understood to have a medium amount of doping.
• a Hall Effect sensing element includes a Hall plate having a thickness less than about 100 nanometers and an adhesion layer directly in contact with the Hall plate and having a thickness in a range about 0.1 nanometers to 5 nanometers.
• the thickness of the Hall plate may be less than about 10 run.
• the Hall plate may have a carrier concentration in a range of about 10 19 to about 10 26 .
• the Hall plate may have a carrier concentration is in a range of about 10 22 to 10 24 .
• the Hall plate may include a metal nitride material.
• the metal nitride material may include at least one of tantalum nitride or titanium oxide nitride.
• the Hall plate may include a metal oxide material.
• the metal oxide material may include a copper oxide.
• the copper oxide may be cuprous oxide.
• the adhesion layer may include ruthenium or ruthenium oxide.
• the Hall Effect sensing element may include a substrate comprising one of a semiconductor material or an insulator material and the adhesion layer disposed between the plate material and the substrate material.
• the Hall Effect sensing element may include an integrated circuit on the semiconductor substrate material.
• the Hall Effect sensing element may include vias connecting the Hall effect sensing element to the integrated circuit from the bottom or substrate side of the Hall effect sensing element.
• the Hall Effect sensing element may include vias connecting the Hall effect sensing element to the integrated circuit from the top or furthest side of the Hall effect sensing element away from the substrate or integrated circuit.
• the semiconductor material may include silicon.
• the insulator material may include at least one of glass or a ceramic material.
• the insulator material may include alumina.
• the insulator material may include an oxide or nitride.
• the Hall Effect sensing element may include a passivation layer directly in contact with the Hall plate.
• the passivation layer may be at least one of a nitride, an oxide, a polymer, a polyimide, or benzocyclobutene (BCB).
• a sensor in another aspect, includes a Hall Effect sensing element.
• the Hall Effect sensing element includes a substrate comprising one of a semiconductor material or an insulator material, an insulation layer in direct contact with the substrate, an adhesion layer having a thickness in a range of about .1 nanometers to 5 nanometers and in direct contact with the insulation layer and a Hall plate in direct contact with the adhesion layer and having a thickness less than about 100 nanometers.
• the adhesion layer may include ruthenium or ruthenium oxide and the Hall plate may include copper oxide.
• the thickness of the Hall plate may be less than about 10 nm.
• the Hall plate may have a carrier concentration is in a range of about 10 22 to 10 24 .
• the Hall plate may include a metal nitride material.
• the metal nitride may include at least one of tantalum nitride or titanium oxide nitride.
• the Hall plate material may be a metal oxide material.
• the metal oxide may include a copper oxide or ruthenium oxide.
• the copper oxide may be cuprous oxide.
• the adhesion layer may include one of titanium, tantalum or ruthenium.
• the semiconductor material may include silicon.
• the insulator material may include at least one of glass or a ceramic material.
• the insulator material may include alumina.
• the sensor may include a passivation layer directly in contact with the Hall plate.
• the passivation layer may be at least one of a nitride, an oxide, a polyimide, or benzocyclobutene (BCB).
• the sensor may be one of a current sensor or a speed sensor.
• a method to manufacture a Hall Effect sensing element includes forming, on a substrate, a plate material having a thickness less than about 100 nanometers and forming an adhesion layer directly in contact with the Hall plate and having a thickness in a range about 0.1 nanometers to 5 nanometers.
• the Hall plate may have a thickness less than lOnm.
• the Hall plate may have a carrier concentration of in a range of about 10 ⁇ to about 10 26 .
• the thickness of the Hall plate may be in a range of about 1 nm to 10 nm and the carrier concentration may be about 10 22 to 10 24 .
• Forming the plate material may include forming a plate material comprising a metal nitride.
• Forming a plate material that includes a metal nitride may include sputtering at least one of tantalum nitride or titanium oxide nitride to form the plate material.
• Forming the plate material may include forming a plate material that may include a metal oxide.
• Forming a plate material that includes a metal oxide may include forming a plate material that includes at least a copper oxide or ruthenium oxide.
• Forming a plate material that includes at least a copper oxide may include sputtering copper in a chamber under vacuum and inserting oxygen into the chamber. Sputtering copper in a chamber under vacuum and inserting oxygen into the chamber may include sputtering copper in a chamber under vacuum while inserting oxygen into the chamber.
• Sputtering copper in a chamber under vacuum and inserting oxygen into the chamber may include sputtering copper in a chamber under vacuum before inserting oxygen into the chamber.
• Sputtering copper in a chamber under vacuum and inserting oxygen into the chamber may include sputtering copper in a chamber under vacuum after inserting oxygen into the chamber.
• FIG. 1 is a cross-sectional view of a Hall Effect sensing element.
• FIG. 2 is a flow diagram of an example to form a Hall plate in the Hall Effect sensing element of FIG. 1.
• FIG. 3 is a diagram of an apparatus used in a sputtering process to form the Hall plate.
• FIG. 4 is an isometric view of a current sensor.
• FIG. 5 is a block diagram of a prior art magnetic field sensor having a magnetic field sensing element, an electronic circuit, and a magnet.
• FIG. 6 is a cross-sectional view of another example of a Hall Effect sensing element
• the Hall plate is formed having a plate material that includes a metal, such as a metal oxide or a metal nitride, for example. Further, the Hall plate may be fabricated that has a thickness of about .5 nanometers to about 100 nanometers. In some examples, the carrier concentration of the Hall Plate is about 10 19 to about 10 26 carriers/cm 3 . In one particular example, the thickness of the Hall plate is less than about 10 nm and the carrier concentration is about 10 22 to 10 24 .
• the Hall element described herein has an increased sensitivity on the order of a ten to a thousand times more sensitive than current Hall elements being used.
• the Hall Effect sensing element 100 is not drawn to scale.
• the Hall Effect sensing element includes a substrate 102, an insulation layer 106, an adhesion layer 110, a Hall plate 114 and a passivation layer 118.
• the insulation material 106 is disposed on the substrate material 102 and the adhesion layer 110 is disposed on the insulation layer 106.
• the adhesion layer 110 enables material used to form the Hall plate 114 to adhere to the insulation layer 106 during a sputtering process, for example.
• the passivation layer 118 is disposed on the plate material of the Hall plate 114.
• the Hall plate 114 may be electrically accessed from the top through vias 122a, 122b or from the bottom through vias 120a, 120b.
• the vias 120a, 120b are shown as through silicon vias (TSVs), but in other embodiments the vias 120a, 120b may only go through the insulating layer to an underlying integrated circuit feature, such as a metal layer or polysilicon layer.
• Process 200 forms the insulation layer (202).
• an oxide, nitride, or a ceramic material such as, for example, silicon dioxide, silicon nitride, or aluminum nitride (or alumina) is deposited on the substrate 102 to form the insulation layer 106.
• the oxide may not be exactly Si0 2 , but some other combination of silicon and oxygen.
• the substrate 102 is a semiconductor material such as silicon, for example.
• the substrate material 102 is an insulator material that includes, for example, at least one of glass, a ceramic material or an alumina.
• the substrate is an integrated circuit, for example a silicon integrated circuit which may include but is not limited to a CMOS, BiCMOS, or other integrated circuit process. Based on the topology of the underlying substrate some embodiments may include a chemical mechanical polishing (CMP), or other planarization step to the substrate or underlying integrated circuit starting material.
• CMP chemical mechanical polishing
• Process 200 deposits an adhesion layer (206).
• an adhesion layer For example, at least one of titanium, tantalum or ruthenium is deposited onto the insulation layer to form the adhesion layer 110.
• the adhesion layer has a thickness from about .1 nanometers to about 5 nanometers. It would be apparent to one of ordinary skill in the art that the thickness of the adhesion material would be such that it does not provide a significant current path for the Hall current to travel through such that the Hall element cannot provide sufficient sensitivity of magnetic field response. This sufficient sensitivity will vary depending on the actual application of the Hall elements described herein.
• the adhesion layer 110 may not be continuous or uniform throughout. For example, there may be gaps in the adhesion layer.
• process 200 deposits a Hall plate material onto the adhesion a layer (212).
• a Hall plate has a thickness in a range of about .5 nanometers to about 100 nanometers and may have a carrier concentration of about 10 19 to about 10 26 .
• the Hall plate has a thickness less than 10 nanometers.
• the Hall plate has a carrier concentration in a range of about 10 22 to 10 24 .
• a metal is sputtered onto the adhesion layer using a sputtering system 300 shown in Fig. 3.
• layer/adhesion layer composite 100' is placed in a chamber 302 with a metal source or target 306 and placed under vacuum by pumping air out through an outlet port 318.
• the metal is a copper or ruthenium.
• a metal nitride is sputtered onto the adhesion layer using the sputter system 300 such as tantalum nitride or gallium nitride and placed under vacuum by pumping air out through the outlet port 318.
• the sputter system 300 such as tantalum nitride or gallium nitride and placed under vacuum by pumping air out through the outlet port 318.
• FIG. 3 only shows one target or metal source 306 for simplicity of the figure.
• a substrate/insulation layer composite is placed in a sputtering or other suitable deposition chamber 302.
• an adhesion layer of Ru of approximately 1 nm in thickness is deposited, followed by a metal such as copper without breaking vacuum between the depositions of the two layers.
• other adhesion layer materials including but not limited to Ru, Ru(3 ⁇ 4, Ti, TIN, Ta, and W, may be used in various combination with different sensing layer materials such as Cu, CdSnO and Ru.
• the metal is combined with oxygen to form a ruthenium oxide or a copper oxide such as cuprous oxide, for example.
• titanium nitride is combined with oxygen to form titanium oxide nitride, for example.
• the oxygen is supplied through an inlet port 312.
• the oxygen may be supplied before, during or after sputtering and the steps may be repeated.
• etch mask layer is a dielectric that includes, for example, an oxide or a nitride such as a silicon nitride material.
• the etch mask layer may be a polyimide, or benzocyclobutene (BCB), or photoresist material.
• Process 200 patterns the Hall plate and the etch mask material (220).
• the Hall plate is etched (222), for example, in an ion beam etching system, or other etching system. In some cases, any polymer materials are then removed, but in other cases the polymer material could remain, for example if a polyimide or BCB material were used to pattern the Hall plate.
• Process 200 deposits a passivation layer (224), which may be, for example, an oxide, nitride, an oxide and nitride layer stack, or a polymer material such as but not limited to a polyimide or BCB.
• a passivation layer 224
• Process 200 forms vias (228).
• a connection may be made to the top of the Hall plate 114 through vias 122a and 122b.
• material down to the plate material is removed and filled with tungsten plugs to form the vias 122a, 122b.
• the vias 122a, 122b may be a bond pad material with an adhesion layer, including but not limited to a titanium adhesion layer with aluminum based via material.
• the bond pad material is deposited into the vias 122a and 122a without first filling the vias 122a and 122b.
• a connection is made from the bottom of the Hall plate 114 using vias 120a, 120b, which may include tungsten plugs.
• the vias 120a, 120b may be a metal interconnection material with an adhesion layer, including but not limited to a titanium adhesion layer with aluminum based via material.
• other standard high conductivity interconnections may be used to connect the Hall plate 114 to the circuit.
• a current sensor is a current sensor 410.
• an example of the Hall Effect sensing element 100 is a Hall Effect sensing element 418.
• the current sensor 410 includes a lead frame 412 having a plurality of leads 412a- 412h.
• the leads 412a and 412b are coupled to the leads 412c and 412d to form a current path, or current conductor with a narrow portion 414 having a width wl .
• the current sensor 410 also includes a substrate 416 having a first surface 416a and a second, opposing surface 416b.
• the Hall Effect sensing element 418 in some examples, may be diffused into the first surface 416a, or otherwise disposed on the first surface 416a.
• the substrate 416 can be comprised of a semiconductor material, e.g., silicon, or, in an alternate embodiment, the substrate 416 can be comprised of an insulating material.
• the substrate 416 is disposed above the lead frame 412 so that the first surface 416a is proximate to the current conductor portion 414 and the second surface 416b is distal from the current conductor portion 414 and more specifically, so that the Hall Effect sensing element 418 is in close proximity to the current conductor portion 414.
• the substrate 416 has an orientation that is upside down (i.e., the first surface 416a is directed downward) relative to a conventional orientation with which a substrate is mounted in an integrated circuit package.
• the substrate 416 has bonding pads 420a-420c on the first surface 416a, to which bond wires 422a-422c are coupled.
• the bond wires are further coupled to the leads 412e, 412f, 412h of the lead frame 412.
• An insulator 424 separates the substrate 16 from the lead frame 412.
• the insulator 424 can be provided in a variety of ways.
• a first portion of the insulator 424 includes a four ⁇ thick layer of a BCB resin material deposited directly on the first surface 416a of the substrate 416.
• a second portion of the insulator 424 may include a layer of underfill material, for example Stay chipTM NUF-2071 E (Cookson Electronics Equipment, New Jersey), deposited on the lead frame 412.
• Such an arrangement provides more than one thousand volts of isolation between the substrate 416 and the lead frame 412.
• the current conductor portion 414 is but a part of the total path through which an electrical current flows.
• a current having a direction depicted by arrows 426 flows into the leads 412c, 412d, which are here shown to be electrically coupled in parallel, through the current conductor portion 414, and out of the leads 412a, 412b, which are also shown here to be electrically coupled in parallel.
• the Hall effect sensing element 418 is disposed in close proximity to the current conductor portion 414 and at a predetermined position relative to the conductor portion 414, such that a magnetic field generated by an electrical current passing though the current conductor portion 414, in a direction shown by arrows 426, is in a direction substantially aligned with a maximum response axis of the Hall Effect sensing element 418.
• the Hall Effect sensing element 418 generates a voltage output proportional to the magnetic field and therefore proportional to the current flowing through the current conductor portion 414.
• the illustrated Hall Effect sensing element 418 has a maximum response axis substantially aligned with a z-axis 434.
• the Hall effect sensing element 418 is disposed just to the side (i.e., slightly offset along a y-axis 432) of the current conductor portion 414, as shown, where the magnetic field is pointed substantially along the z-axis 434. This position results in a greater voltage output from the Hall Effect sensing element 418, and therefore improved sensitivity.
• a Hall effect sensing element or another type of magnetic field sensor, for example a magnetoresistance element, having maximum response axis aligned in another direction, can be disposed at another position relative to the current conductor portion 414, for example, on top of the current conductor portion 414 (in a direction along z-axis 434).
• Hall Effect sensing element 418 is shown on the first surface 416a of the substrate 416, it will be appreciated that more than one Hall Effect sensing element can be used. Also, additional circuitry, for example an amplifier, can also be diffused in or otherwise disposed on, or supported by the first and/or second surfaces 416a, 416b of the substrate 416.
• the close proximity between the Hall Effect sensing element 418 and the current conductor 414 is achieved by providing the Hall Effect sensing element 418 on the first substrate surface 416a, which is positioned closer to the current conductor portion 414 than the second surface.
• this advantageous close proximity is achieved by providing the Hall effect sensing element 418 on the second substrate surface 41 b and forming the current conductor portion 414 so as to be in substantial alignment with the second surface 416b.
• current sensor 410 could also be flip chip assembled with solder balls, bumps, or stud bumps of copper.
• wire bonds are shown as the connection method in FIG. 4, it would be possible to provide a connection between the die and leadframe using a flip chip process.
• the connection of the die to the leadframe is typically achieved via a reflow step.
• a conductive epoxy adhesive is used at designated locations to connect the leadframe to the die.
• a lead on chip process could also be used. This process is one where the leadframe is over the die and then electrical connection may be made from the top surface of the leadframe to the top surface of the die where these two surfaces are facing the same direction.
• the width wl (FIG. 4) is selected in accordance with a variety of factors, including, but not limited to a desired sensitivity of the current sensor 410 (FIG. 4), and a desired reduction of performance variation resulting from manufacturing variation in relative position of the current path 414 and the Hall effect sensing element 418.
• selecting the width wl to be comparable to a width of the Hall Effect sensing element 418 provides the greatest sensitivity of the current sensor 410.
• selecting the width wl to be greater than the width of the Hall Effect sensing element 418 provides the smallest performance variation resulting from manufacturing tolerance of Hall element positional placement in the x- direction 430.
• an example of a speed sensor is a magnetic field sensor 510.
• an example of the Hall Effect sensing element 100 is a Hall Effect sensing element 512.
• multiple Hall Effect sensing elements may be used to determine either one or both of direction and vibration in addition to speed.
• the magnetic field sensor 510 is responsive to a gear 522 having ferromagnetic gear teeth, e.g., gear teeth 522a, 522b, 522c.
• gear 522 is but one type of "ferromagnetic target object," or simply "target object,” which the magnetic field sensor 510 can be responsive.
• the ferromagnetic target object may include a permanent magnet (or a hard ferromagnetic material), for example, the above-described ring magnet having alternating north and south poles.
• the magnetic field sensor 510 includes a magnetic field sensing element 512 coupled to an electronic circuit 516.
• the magnetic field sensing element 512 and the electronic circuit 516 can be disposed upon (i.e., integrated within or upon) a substrate 514.
• the Hall Effect sensing element 512 is shown with an exaggerated size, and rotated out of the plane of the substrate 514.
• the Hall Effect sensing element 512 is shown to be on top of the substrate 514, but it will be appreciated that Hall Effect sensing elements are usually disposed upon or within a surface of a substrate of an integrated circuit. In other embodiments, the Hall Effect sensing element(s) could be located on the opposite surface of the die from the circuitry by the use of through silicon vias (TSVs).
• TSVs through silicon vias
• the magnetic field sensor 510 can also include a magnet 518 (e.g. a permanent magnet or hard ferromagnetic material).
• the magnet 518 is configured to generate a magnetic field, which is generally directed along an axis 524 at the position of the Hall Effect sensing element 512, and which is subject to direction and amplitude changes depending upon positions of the gear teeth 522a, 522b, 522c relative to the magnetic field sensor 510.
• the structure of the magnetic field at faces of the magnet 518 can be more complex due to a core 520.
• the magnetic field may be produced by a magnetic element without a core.
• the magnetization or direction of magnetic field from the magnet may be different than generally parallel to the axis 524, for example perpendicular to the axis 524, or at any other angle.
• the electronic circuit 516 is configured to generate an output signal (not shown).
• the output signal when the gear is not moving, is indicative of whether the magnetic field sensor 510 is over a gear tooth or a gear valley.
• the magnetic field sensor 510 is sometimes referred to as a "tooth detector” (or feature detector) as opposed to an “edge detector.”
• the output signal when the gear is rotating, has an edge rate or a frequency indicative of a speed of rotation of the gear. Edges or transitions of states of the output signal can be used to identify positions of edges of the gear teeth as they pass by the magnetic field sensor.
• the sensor may not be able to detect the presence or absence of a tooth, but rather only be used for detection of speed or a change in position of a target.
• the magnet 518 can include the central core 520 comprised of a soft ferromagnetic material disposed within the magnet 518.
• a magnet with a core is described in U.S. Patent No. 6,278,269, entitled “Magnet Structure,” issued August 21, 2001 , which patent is assigned to the assignee of the present invention and incorporated herein by reference in its entirety.
• the pole configuration provided by the magnet 518 with the core 520 lowers the base field (or baseline) of a flux density of the magnetic field at some points above the surface of the core 520 (e.g., to the left of the core as shown) when a valley of the gear 522 is proximate to the magnetic field sensor 510.
• a predetermined baseline (e.g., within a range of about +/ six hundred Gauss) at the Hall effect sensing element 512, and a resulting differential magnetic field signal 512a, 512b (i.e., an analog differential proximity signal) near zero, can be achieved with proper design.
• the magnet may not have a central soft ferromagnetic core, but rather an air core.
• Other embodiments may be found in U.S. Patent Publication Number 2014-0320124, entitled “INTEGRATED CIRCUIT PACKAGE HAVING A SPLIT LEAD FRAME AND A MAGNET," published October 30, 2014 and U.S. Patent Publication Number 2013-0249546, entitled "INTEGRATED CIRCUIT PACKAGE HAVING A SPLIT LEAD FRAME," published September 26, 2013, which are incorporated herein in their entirety and assigned to the same assignee as the present application.
• the Hall element 512 experiences a higher magnetic field and generates the differential magnetic field signal 512a, 512b with a higher value.
• a difference between the baseline magnetic field and the higher magnetic field is related to ultimate accuracy of the magnetic field sensor 510.
• the baseline magnetic field which can occur when the magnetic field sensor 510 is proximate to a valley in the gear 522, remains relatively low, with little change, even as the air gap between the gear 522 and the magnetic field sensor 510 varies.
• This advantageous result of low baseline substantially independent of air gap is achieved by operation and design of the core 520 (including an air core), which results in opposite magnetic poles being presented at the face of the core 520 (i.e., left side as shown) proximate to the magnetic field sensing element 512, particularly when the Hall effect sensing element 512 is proximate to a valley in the gear 522.
• This effect is also described in U.S. Patent Number 5,781,005, issued July 14, 1998, entitled "Hall-Effect
• Ferromagnetic- Article-Proximity Sensor which patent is assigned to the assignee of the present invention and incorporated herein by reference in its entirety.
• the above-described low baseline also provides an ability to more easily compensate for temperature effects, since the baseline magnetic field is relatively small, and therefore, circuit variations that occur due to temperature can have less influence when the magnetic field sensor 510 is proximate to a valley in the gear 522. Essentially, any error in the circuitry is able to be well corrected near the baseline magnetic field level or range, since any multiplication of the error (near zero) is smaller. Therefore, a magnetic field threshold used to distinguish a tooth from a valley can be made smaller while maintaining precision because there is less noise or error in the system over its operating conditions such as temperature, or humidity.
• FIG. 6 another example of a Hall Effect sensing element with a Hall plate that improves sensitivity is a Hall Effect sensing element 100'.
• the Hall effect sensing element 100' is not drawn to scale.
• integrated circuits 105 are depicted in the substrate 102 and the integrated circuits are coupled to the Hall plate 114 through vias 120a, 120b.
• process 200 is not limited to the specific processing order of FIG. 2. Rather, any of the processing blocks of FIG. 2 may be re-ordered, combined or removed, performed in parallel or in serial, as necessary, to achieve the results set forth above.

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